The IEEE 802.3ah specification describes an Ethernet OAM specification that is intended for point-to-point and emulated point-to-point IEEE 802.3 links. Those skilled in the art will appreciate that IEEE 802.3ah and IEEE 802.3 refer to sets of specifications that are available from the Institute of Electrical and Electronics Engineers.
A point-to-point link might be between Customer Premises Equipment (CPE) and an Ethernet Bridge/Switch, for example, where the Ethernet Bridge/Switch terminates both the point-to-point link and any OAM packets received from the CPE. Point-to-point links are not limited to direct physical links between two nodes, but can also be extended to a connection between two nodes across a logical link, such as an Ethernet PseudoWire (PW) over a Multi-Protocol Label Switching (MPLS) network or an Ethernet Soft Permanent Virtual Circuit (SPVC) in an Asynchronous Transfer Mode (ATM network). In this case, a Provider Edge or PE node terminates the logical link, but might not terminate OAM packets received from a CPE. The PE node may instead tunnel an OAM packet to reach the far end PE node, which in turn may forward the OAM packet to its associated CPE.
Configuration of one or both PE nodes to terminate, instead of tunnel, OAM packets on their Ethernet Attachment Circuits (ACs) that provide a logical Ethernet path between two CPEs, for example, can lead to improper handling of OAM packets. According to current IEEE 802.3ah specifications, for instance, OAM packets are sent only on point-to-point links over a single hop. If a PE node in a path between two CPEs terminates OAM packets, then OAM packets intended to manage the complete CPE-to-CPE communication path are terminated at an intermediate point along the path, and thus do not have the desired effect of managing the complete path. Detection of such misconfigurations, however, can be difficult since current specifications and products do not provide any mechanisms for intermediate PE nodes or other equipment to exchange indications of their respective configurations.